Impala Class Close Escort (LBB2 2nd Ed)

[Grav_Moped]

This is as close to the idea of the Gazelle class as I can get under LBB2, for LBB2. Jump capability without tanks requires invoking the TCS/JTAS#14 power-down rule. Drop tanks are backported from LBB5, but that is the only component from LBB5 used.
Cost does not include the Fast Gig (6G, Mod/2, 2 missiles, 1 beam laser, 7Td payload -- LBB5 build, TL-11) carried internally.

200Td plus 200Td of drop tanks.
Performance:
With tanks retained, 3G/J2/P3+an extra drive letter; can do two J2 plus 1J1.
With tanks ejected during Jump, J5
With tanks not installed, 6G/J0/P6+an extra drive letter
Note that underloading the power plant to Pn-2 (that is, not exceeding J2 or 2Gs) allows one J2 on internal tankage).

2 Turrets: 1 triple missile, 1 triple beam laser. Lasers can be double-fired due to excess power plant capacity.

6Td cargo.

Carries a 20Td Fast Gig (6g, Mod/2, 1.8Td fuel, LMM turret equivalent, 7Td payload) internally.

Streamlined, includes fuel scoops, military drives can use unrefined fuel.

Crew:
Officers: Pilot, Engineering Officer, Gunnery Officer, Fast Gig Pilot
Enlisted: Navigator, Medic, Engineer, Gunner, Fast Gig Gunner
(One half-stateroom intentionally left unoccupied).

MCr 209.66 individually, excluding the Fast Gig. TL-11 (Mod/5 computer is limiting factor).

Item     Tons  MCr    Comments
Bridge    20     2
Mod/5      5    45    Not fib since LBB2 doesn't track radiation damage
SRx7      28     3.5  4 officers single PEG+P(SC), 5 ratings double NMGE+G(SC).
Jump E    30    50    J2/J5
Power G   22    56    P3/P7 (Rating maxes at at P6, but allows Double-Fire)
M-D F     11    24    3G/6G
J-Fuel   200     0.2  All in drop tanks
P-Fuel    60     0    Internal.  Fuel use as Pn-6. Idle to Pn2 allows J2 w/o tanks.
Hull       0    22    200Td LBB2 streamlined custom (the rest is drop tanks)
Turret 1   1     4.1  Triple Beam Laser
Turret 2   1     3.35 Triple Missile
Gig       20 Excluded 6G, 1.2EP, Mod/2, 1.8Td fuel, LMM, 7Td payload
Cargo      6     0
Total:   400   209.16

 

[AnotherDilbert]

Easier to do with larger ships, with relatively smaller steps in the drive performance table, e.g.:

400 Dt + 200 Dt drop tank = 600 Dt.
J4, M4 with tanks.
J6 dropping tanks.
J1, M6 without tanks (or J2, M2 powered down)
100 Dt payload free.

EL-4366662-030000-10001-0        MCr 383         400 Dton    Ag=6
EL-6344462-030000-10001-0        MCr 383         600 Dton
bearing     4     4   4                           Crew=11
batteries   4     4   4                             TL=12
             Cargo=111 Fuel=100 EP=24 Agility=2 DropT=200

Dual Occupancy      LBB2 design                     111       383
                                     USP    #      Dton      Cost
Hull, Part Streaml  Custom             4            400     
Configuration       Cylinder           3                       40
                                                            
Drop Tanks          200 Dton                                    0
Total tonnage       600 Dton                                 
                                                            
Jump Drive          M                  4    1        65       120
Manoeuvre D         M                  4    1        23        48
Power Plant         N                  4    1        40       104
Fuel, #J, #weeks    J-4, 4 weeks            4       100     
                                                            
Bridge                                      1        20         2
Computer            m/6                6    1         7        55
                                                            
Staterooms                                  4        16         2
Staterooms, Half                            7        14         2
                                                            
Cargo                                               111     
                                                            
Mixed Turret        Full                    4         4         4
  Weapon            Missile            1    1                   3
  Weapon            Pulse              1    1                   2
  Weapon            Sand               3    1                   1
                                                            
Nominal Cost        MCr 383,36           Sum:       111       383
Class Cost          MCr  42,17          Valid        ≥0        ≥0
Ship Cost           MCr 345,02                               
                                                            
                                                            
Crew &               High     0        Crew          Bridge     2
Passengers            Mid     0          11       Engineers     4
                      Low     0                     Gunners     4
                 Extra SR     0      Frozen         Service     1
               # Frozen W     0           0          Flight     0
                  Marines     0                     Marines     0

Same ship works just as well with two tanks:

EL-4366662-030000-10001-0        MCr 384         400 Dton    Ag=6
EL-8333362-030000-10001-0        MCr 384         800 Dton
bearing     4     4   4                           Crew=11
batteries   4     4   4                             TL=12
            Cargo=111 Fuel=99,9 EP=24 Agility=1 DropT=400

Dual Occupancy      LBB2 design                     111       384
                                     USP    #      Dton      Cost
Hull, Part Streaml  Custom             4            400       
Configuration       Cylinder           3                       40
                                                              
Drop Tanks          400 Dton                                    0
Total tonnage       800 Dton                                   
                                                              
Jump Drive          M                  3    1        65       120
Manoeuvre D         M                  3    1        23        48
Power Plant         N                  3    1        40       104
Fuel, #J, #weeks    J-3, 6,7 weeks          3       100

Or three tanks:

EL-4366662-030000-10001-0        MCr 384         400 Dton    Ag=6
EL-A322262-030000-10001-0        MCr 384       1 000 Dton
bearing     4     4   4                           Crew=11
batteries   4     4   4                             TL=12
             Cargo=111 Fuel=100 EP=24 Agility=1 DropT=600

Dual Occupancy      LBB2 design                     111       384
                                     USP    #      Dton      Cost
Hull, Part Streaml  Custom             4            400         
Configuration       Cylinder           3                       40
                                                                
Drop Tanks          600 Dton                                    1
Total tonnage       1 000 Dton                                   
                                                                
Jump Drive          M                  2    1        65       120
Manoeuvre D         M                  2    1        23        48
Power Plant         N                  2    1        40       104
Fuel, #J, #weeks    J-2, 6,7 weeks          2       100

You can do really long range ships with Z-drives and several drop tanks...

 

[Grav_Moped]

You can do really long range ships with Z-drives and several drop tanks...

Never tried that with Z-drives, but I did up a rift-crossing drop tank design exercise several years ago.

I managed 20 parsecs unrefueled based on a 400Td J-5 core ship with 1600Td of drop tanks (including 20Td of disposable "bridge" to meet the 2% requirement).

Spoiler: Details under the spoiler tag

Core ship was JD-K, PP-K, MD-B, 12Td cargo. It could not maneuver with tanks installed.

The three drop tanks were: 1600Td (1580 fuel + 20Td bridge), 400Td, 200Td. Jump ranges were J1 all-up, J2 @ 1000Td, J3 @ 600Td, J5 @ 400Td (core ship).

Jumps were:
- 3J1 with all three tanks. (3 parsecs from origin after this.)
- 1J2 while dropping the 1600Td tank (leaves 160Td fuel behind). (5 parsecs from origin after this.)
- 1J2 retaining remaining tanks. (7 parsecs from origin after this.)
- 1J3 while dropping 400Td tank (leaves 10Td fuel behind.) (10 parsecs from origin after this.)
- 1J5 while dropping 200Td tank. (15 parsecs from origin after this.)
- 1J5 on internal tanks. (20 parsecs from origin after this, and we're done.)

Ship finishes the 20-parsec run in 8 weeks (J2.5 pace), with two weeks power plant fuel remaining.

A set of 3 mid-rift fuel caches would be a much less expensive alternative.

On the other hand, this would allow going 10 parsecs out and returning, without external support -- and the return trip only takes two weeks. It could be useful for long-range reconnaissance. It's also slightly faster over long distance than even a Collector-3 ship.

 

[Grav_Moped]

Easier to do with larger ships, with relatively smaller steps in the drive performance table

True.

I constrained myself by keeping it close to the 400Td Gazelle, though.

The only "creative" parts here were exploiting the TCS/JTAS#14 power-down rule to get J2 out of the Pn-6 fuel tankage in the "clean" configuration, and using the "Pn rating cannot exceed 6" rule to save 10Td fuel while having a power plant big enough to enable the use of the Double-Fire program. It's streamlined because LBB2 doesn't do "partially streamlined" hulls.

To reiterate, this is a LBB2 design for use in LBB2 space combat. If I weren't specifically making this a Gazelle analog, I'd consider replacing the 20Td Fast Gig with 2 Ea. 10Td fighters.

It's probably a self-propelled target under LBB5 rules...

 

[AnotherDilbert]

The only "creative" parts here were exploiting the TCS/JTAS#14 power-down rule to get J2 out of the Pn-6 fuel tankage in the "clean" configuration, and using the "Pn rating cannot exceed 6" rule to save 10Td fuel while having a power plant big enough to enable the use of the Double-Fire program.

Counterintuitively a G drive in a 200 Dt hull results in no potential by RAW:

LBB2'81, p13:
It is important to note from the drive potential table that some drives will not produce results in some tonnages of hulls, as indicated by a dash instead of a number on the table;

If a drive is too small or too large, it doesn't work at all.

LBB2 is just being LBB2...

To reiterate, this is a LBB2 design for use in LBB2 space combat. If I weren't specifically making this a Gazelle analog, I'd consider replacing the 20Td Fast Gig with 2 Ea. 10Td fighters.

I'm no expert in LBB2 combat, but I have the impression that it's mostly about piling on more weapons, hence turrets. Though a Gig with a computer might be better than a light fighter with a minimal computer. So, having two turrets against a regular 400-tonners four would be a critical flaw in combat, I suspect.

I have vague memories of large (1000 Dt+?) ships killing each other in the first round due to weapons (hence hits) increasing faster than damage-soaking capability, but I might very well be wrong.

 

[Grav_Moped]

If a drive is too small or too large, it doesn't work at all.

LBB2 is just being LBB2...

This implies that ships with 6G acceleration capability can never use the Double-Fire program, which seems silly. It's not that they don't work, it's that you can't get a factor greater than 6 so there's no point unless you're going for Double-Fire capability, or want an oversized drive as a sort of "armor" or damage buffer.

More to the point, it would mean that if this ship had 4G capability with 200Td of tanks installed (400Td configuration) and then dropped them, the maneuver drive would somehow cease to function.

I'm no expert in LBB2 combat, but I have the impression that it's mostly about piling on more weapons, hence turrets. Though a Gig with a computer might be better than a light fighter with a minimal computer. So, having two turrets against a regular 400-tonners four would be a critical flaw in combat, I suspect.

The Double-Fire capability effectively adds a third turret, the gig a fourth. And in fighting trim, it's a 200Td ship (or will be as soon as it takes a fuel hit!)

Fighters without computers or separate gunners are at a disadvantage. I'm not entirely sure if a small craft can gain much benefit from a computer larger than Mod/3 under LBB2 computer rules. After all, there are only a finite number of offensive/defensive programs to run.

 

[mike wightman]

Look at the 400t row - a ship with a 6g M m-drive but an N power plant can get double fire because its letter rating is higher.

Double fire allows a ship to draw excess power (if available) from the power
plant and thus increase the output of laser weaponry. When this program is functioning,
a vessel with a power plant rated at least one letter higher than its maneuver
drive (and which has not yet taken damage to reduce the current letter rating to
equal to or below the M-drive letter) can fire a double beam or double pulse with
laser weaponry.

 

[Grav_Moped]

Look at the 400t row - a ship with a 6g M m-drive but an N power plant can get double fire because its letter rating is higher.

In this case, it's a PP-G over a MD-F (6G/Pn-"not 7 but..." for the 200Td core hull).

 

[AnotherDilbert]

Not only it's not a PP-7, it's not a PP-6. It's a PP-"no result".

 

[Grav_Moped]

Not only it's not a PP-7, it's not a PP-6. It's a PP-"no result".

Dropping the external fuel tanks makes the power plant cease to function (or possibly, retroactively cease to exist). That seems perfectly reasonable.

I mean, I get where you're coming from. But it's silly.

 

[Grav_Moped]

That said, it's not entirely silly. Using this edge case to get double-fire functionality under LBB2 rules isn't unreasonable.

The extension of this to allowing LBB2 power plants to consistently have ratings higher than 6 would completely unbalance the TL progression in LBB5, though.

 

[coliver988]

That said, it's not entirely silly. Using this edge case to get double-fire functionality under LBB2 rules isn't unreasonable.

The extension of this to allowing LBB2 power plants to consistently have ratings higher than 6 would completely unbalance the TL progression in LBB5, though.

Could just be handwaved that you can only get a max of 6 even if overpowered as the ship's frame won't take more than that (no ship integrity fields in Traveller!) but it is a might big handwave Anything above that is throttled, except for the double-fire. Yeah, big hand-wave

 

[AnotherDilbert]

Dropping the external fuel tanks makes the power plant cease to function (or possibly, retroactively cease to exist). That seems perfectly reasonable.

I mean, I get where you're coming from. But it's silly.

Yes, it's completely silly. Yet RAW...

As I said before:

LBB2 is just being LBB2...

 

[Grav_Moped]

Could just be handwaved that you can only get a max of 6 even if overpowered as the ship's frame won't take more than that (no ship integrity fields in Traveller!) but it is a might big handwave Anything above that is throttled, except for the double-fire. Yeah, big hand-wave

The point is that the only performance benefit of having an oversized power plant (relative to Jump or Maneuver Drive size) in LBB2 is the ability to use Double-Fire. Energy usage isn't even tracked, otherwise.

(Yes, it's also expensive "drive armor".)

Oversized power plants are a big thing in LBB5, though.

 

[kilemall]

That said, it's not entirely silly. Using this edge case to get double-fire functionality under LBB2 rules isn't unreasonable.

The extension of this to allowing LBB2 power plants to consistently have ratings higher than 6 would completely unbalance the TL progression in LBB5, though.

LBB5 doesn't matter if you are strictly playing by LBB2, which using the computer software enabling Double Fire strongly suggests.
Don't know if that's true either, the power plant is physically bigger and costs more so it's like having a PP-7 and M-6, with a home ruled provision for some sort of extra fire built into power allocation.

I would say that is an implicit option designed in so getting that second ship custom-built gets options like powered up double fire plants. Another incentive to pile up the megacredits to get a ride with some edges built in.

Big payoff to load a personal warship with double fire, best missiles possible, and the best computer and software one can afford.

 

[infojunky]

Heh, I was just pondering the other day what the precursors to the Gazelle Close Escort would look like.

My intial ballpark was 400 ton J3 M3 with a mix of Plasma guns and lasers as armament.

 

[AnotherDilbert]

Dropping the external fuel tanks makes the power plant cease to function (or possibly, retroactively cease to exist).

Reading the rules literally enough, we don't actually need a working power plant, just equal or higher drive letter than M-drive or J-drive. We could make a 200 Dt ship with a power plant G, while completely legal would give a power plant potential of 0 and hence no need for power plant fuel.

LBB2 is just being LBB2...

 

[Grav_Moped]

LBB5 doesn't matter if you are strictly playing by LBB2, which using the computer software enabling Double Fire strongly suggests.
Don't know if that's true either, the power plant is physically bigger and costs more so it's like having a PP-7 and M-6, with a home ruled provision for some sort of extra fire built into power allocation.

I would say that is an implicit option designed in so getting that second ship custom-built gets options like powered up double fire plants. Another incentive to pile up the megacredits to get a ride with some edges built in.

Big payoff to load a personal warship with double fire, best missiles possible, and the best computer and software one can afford.

It's absolutely a LBB2-only ship -- that's precisely the point.

Though in retrospect, it's more a Fiery analog than a Gazelle analog, since the former is the fully-streamlined version of the on-paper build. Maybe the class should be Camary or Corvetty instead?
Theme: Chevrolet sports car names, but replacing the terminal vowel with "y". But canon doesn't say anything about the Fiery class inevitably having one pop-up turret permanently stuck in the deployed position...

Anyhow. LBB5 incorporates LBB2 drives. The "no drive ratings above 6" characteristic of the Drive Potential table provides a hard limit to exploiting LBB2 drives in LBB5 designs -- basically, you can't get Agility 6 in any LBB5 ship with LBB2 drives that has a computer larger than a Mod/2, or any energy weapons.

 

[Grav_Moped]

So, what does this ship look like?

If it's a Gazelle analog, the drives get moved inboard to the main hull, and the massive drop tanks run along the sides of the ship for almost its whole length.

If it's a Fiery analog (and it is), I'm thinking more along the lines of a needle with a large delta wing (containing the integral fuel tanks and the drives) and underslung long prolate spheroid drop tanks.

If I'm doing it as a clean sheet, maybe like a V-2 rocket with the fins continuing about halfway up, and 4 slender 50-ton drop tanks attached one to each fin. And as a tailsitter, of course.

VERY crude sketch (and the main hull might do well to be skinnier).
Main hull is about 10m diameter and 40m tall (about 155Td), 45Td of the drives are in the "fins" between the main hull and drop tanks.
50Td drop tanks are roughly modeled on 30m x 6m 50Td Cutter.
(Yes, this is a nudge to @Spinward Flow...)

Having a little difficulty figuring out how to get the 20Td Gig out the side between the drop tanks, but I bet it's not that tricky if you look at it from a top/front view. It's late though, so I suppose I'll get to it in the morning. Weapon fields of fire are another matter.

 

[AnotherDilbert]

Anyhow. LBB5 incorporates LBB2 drives. The "no drive ratings above 6" characteristic of the Drive Potential table provides a hard limit to exploiting LBB2 drives in LBB5 designs -- basically, you can't get Agility 6 in any LBB5 ship with LBB2 drives that has a computer larger than a Mod/2, or any energy weapons.

You can use LBB2 drives with a LBB5 power plant in a LBB5 ship.